Stoker



Feb. 19 1935.' w. D. BURTON STOKER Filed Dec. 29, 1930 "45 marine type having a long and relatively shallow UNITED STATES PATENT 1,991,241 s'ronsa Warren Dean Burton, Goshen, Incl, assigncr to @ombustioneer, Inc., Goshen, but, a corporation of Illinois Application December 29, 193%, Serial No. 505,23it

7 @laims, (Cl. lit-47) This invention relates to mechanical stokers a horizontal conduit 9 which extends forwardly for furnaces and more particularly to those of through the front wall of the furnace and comjthe underfeed type wherein coal is fed into the municates with a hopper 10 from which coal is furnace by a conveyor screw and forced upfed in the operation of the power driving mechawardly thereby into a retort where it is consumed. nism 11 of the Stoker. 5

When stokers oi the above character are ap- Within the conduit 9 is a rigid shaft 12 carplied to Scotch marine boilers, it is necessary rying flights 13 of a diameter slightly less than that the retort be made relatively long and narthe conduit 9 and defining a screw for conveying row. A correspondingly long section of the concoal from the hopper along the conduit and 10 veyor screw is left exposed in the bottom of the into the retort in the normal rotation of the stoker lb retort and by reason of its length severe bending motor 14. The outer end of the shaft 12 is rotatstresses are exerted in the intermediate portion ably Supported in the usual way by the frame of f of this section by the upward wedging action of the power unit 11 and the inner end projects the coal which becomes packed beneath the screw. a short distance into the lower portion of the 15 One object of the present invention is to proretort. it vide a new and improved conveyor screw for un- Longitudinally alined with the screw above de-' derfeed stolzers which is particularly adapted to scribed is a second rigid shaft 15 of shorter length withstand the strains to which it becomes subdisposed wholly within the retort and having jected when used in a stoker for a Scotch marine flights 16 of an inclination similar to the flights boiler. l 13 but of a smaller diameter and preferably taperso More specifically stated, the invention aims to ing slightly toward its rear end. The latter end provide an underreed stoker having a conveyor of the shaft 15 is received in a cylindrical bear screw composed of two axially alined sections ing Socket 1'! defined by the rear concave wall which are joined within the furnace-retort by a of the retort and carries a screw flight 18 which coupling permitting of lateral fiexure of the screw rotates loosely in the socket. d5 sections relative to each other. At its forward end, the shaft 15 is joined to Another object is to provide a novel bearing the adjacent end of the shaft 12 by a coupling for supporting the inner end of the conveyor screw 19 which preferably permits some degree of uniin an underfeed stolrer whereby clogging of the .versal movement between the two shafts so that bearing by accumulating coal dust is effectually .the conveyor screw may flex slightly at a point 3% ,avoided. near .the center of the retort thereby relieving Other objects and advantages of the invention the severe lateral stress to which this part of the will become apparent from the following detailed screw becomes subjected while forcing coal updescription taken in connection with the accomwardly through the retort opening. It will be panying drawing, in which, v observed that the hearing at the rear of the shaft 355 Figure l is a vertical sectional view of aboiler l5 permits of such limited upward movement of equipped with a Stoker embodying the features of the coupli FFlCE the present invention. Inasmuch as the rear section of the conveyor Fig. 2 is a fragmentary plan view of the stoker screw is of relatively smaller diameter and tapers 40 retorttoward its rear end, the capacity of this section Fig. 3 is a sectional view taken along the line is correspondingly decreased with the result that 3- of 1. the coal will be distributed evenly along the en- 111 the exemplary Q m the Gram, tire length of the retort opening thereby avoiding the invention is embodied in a boller of the Scotch restriction f the shallow combustion Space.

In order to prevent dust and small particles horizontal combustion space 5 in which a bed of coal from clogging the rear bearing of the fuel is suppprted by retort comprising an conveyor, the screw flight 18 is inclined reversely gig 'ggg g gi ig gg g gsg fi ggg iig gg to the flights 16 and therefore operates automati- 5 conform to the shape of the combustion space, the 1 m the normal rotation of the convFyor screw retort is made relatively shallow and its top opentolwlthdraw from the f a tending is long and narrow. ing to accumulate therein. The provision of such Communicating with the lower portion of the a means for preven'fimg c o S particularly .retort and extending forwardly from its front wall imp r in the Present instance in View of the 55 is a tubular projection 8 into which is received fact that some degree of play must be provided I.

for at the bearing in order to allow for relative flexing of the bearing sections.

By forming the conveyor screw in two rigid sections coupled together as above described, it will be apparent that I have eliminated the danger of breaking the conveyor screw by packing of coal beneath the screw when the same is used in such a long retort as is required in furnaces of the Scotch marine type. Assembly of the conveyor is also greatly facilitated because it is unnecessary to aline its supporting bearings.

I claim as my invention:

1. In an underfeed stoker, the combination of an upwardly opening retort having an inwardly opening bearing socket in its rear wall, a rotary screw; shaft projecting into the lower portion of said retort with its inner end disposed in said socket, and flights on said inner end rotatably supporting said end in said socket and inclined to convey accumulating coal dust out of said socket during rotation of said screw shaft in a direction to advance coal into said retort.

2. In an underfeed stoker, the combination of an upwardly opening retort having a rear wall, a bearing sleeve in said rear wall opening to said retort, a rotary screw projecting into the lower portion of said retort and having its inner end extending into said sleeve, said screw being operable to advance fuel into said retort toward said Wall, and means on said inner end of said screw rotatably supported in said sleeve and operable as an incident to the normal rotation of said screw to expel from said sleeve any fuel tending to accumulate therein.

3. In an underfeed stoker, the combination of an upwardly opening retort having an inclined rear wall formed with an inwardly opening cylindrical bearing socket substantially closed at its outer end, a shaft projecting into said retort with its inner end extending into said socket, flights on said shaft defining screw means for advancing fuel into said retort'toward said rear wall, and reverse flights on said inner end of said shaft rotatably supported in said socket and defining screw means for expelling any fuel tending to accumulate in said socket.

4. In a stoker, the combination of a retort having an inlet opening in one side thereof, a first screw extending through said opening into said retort, a second screw in said retort flexibly coupled at one end to the inner end of said first screw, a bearing in said retort, and reverse screw flights on the other end of said second screw and vsaid socket.

loosely supported for rotation in said bearing to prevent coal dust from accumulating in said bearing.

5. In an underfeed stoker, the combination of a horizontal retort discharging upwardly and having a horizontal inlet opening in one wall and an inwardly opening bearing socket in an opposite wall, a rotary screw shaft extending through said opening into said retort, and reverse screw flights on the inner end of said shaft and rotatably supported in said socket to prevent the packing of fuel in said socket, an intermediate portion of said shaft being positioned above the bottom of said retort and having a flexible coupling interposed therein.

6. In an underfeed stoker, the combination of a horizontal retort discharging upwardly and having a horizontal inlet opening in one wall and an inwardly opening bearing socket in an opposite wall, a first shaft with rotary screw flights extending through said opening into said retort, a second shaft with rotary screw flights having a lead in the same direction as said first mentioned flights, and extending above the bottom of said retort and in substantial axial alignment with the inner end of said first mentioned shaft,

a universal coupling connecting the adjacent ends of said shafts, and reverse screw flights on the remote end of said second shaft rotatably supported in said socket and operative to prevent the packing of fuel in said socket.

7. In an underfeed stoker, the combination of a horizontal retort discharging upwardly and having a horizontal inlet opening in one wall and an inwardly opening bearing socket in an opposite wall, a first shaft with rotary screw flights extending through said opening into said retort, a second shaft with rotary screw flights having a lead in the same direction as said first mentioned flights, and extending above the bottom of said retort and in substantial axial alignment with the smaller in diameter than said first mentioned flights and being tapered toward the end of said second shaft remote from said coupling, and reverse screw flights on said remote end of said second shaft rotatably supported in said socket and operative to prevent the packing of fuel in WARREN DEAN BUR'IDN. 

